The present invention relates to a sheet feed apparatus for use with copying apparatus.
For example, in a copying machine, when recording sheets with different sizes, such as A series sizes and B series sizes, are selectively used, it will be better to install a sheet feed apparatus capable of feeding the recording sheets of various sizes in the copying machine rather than to install several sheet feed apparatuses for use with the recording sheets of different sizes, in view of making the copying machine compact in size.
However, in the case where the recording sheets of various sizes are fed from one sheet feed apparatus, the most difficult point is to set a sheet feed roller at the most proper position in accordance with the size of each recording sheet.
Conventionally, as an example of the sheet feed apparatus capable of feeding the recording sheets of different sizes, a one-side line-up system is known, in which the feeding direction of the recording sheets is determined by utilizing one side of the recording sheets as a standard line. In the one-side line-up system, on the side of a standard line, there is disposed one sheet feed roller, and on the other side, there are disposed two sheet feed rollers (i.e., an inner roller and an outer roller). These sheet feed rollers are arranged coaxially, and the recording sheets of A sizes are fed by the sheet feed roller on the standard line side and by the inner roller, while the recording sheets of B sizes are fed by the sheet feed roller on the standard line side and the outer roller. However, when the recording sheets of B sizes are fed, the three rollers including the inner roller are used. Therefore, a non-uniform feeding force is applied to the opposite sides of the recording sheets of B sizes by the three rollers. Therefore, the conventional system has a disadvantage of frequently causing a skew in the feeding of recording sheets and the images on the recording sheets are deformed.
In an apparatus belonging to the one-side line-up system, a first sheet feed roller on the standard line side is fixedly mounted on a shaft, and a second sheet feed roller is mounted on the shaft so as to be movable in the axial direction of the shaft, and the second sheet feed roller is moved appropriately in the axial direction of the shaft in accordance with the size of the recording sheets. The second sheet feed roller is moved manually whenever the recording sheets of different sizes are employed. However, it is not easy to move the second sheet feed roller since it is positioned inside the body of a copying machine.